The Domain Name System, or DNS, is a naming scheme for dotted decimal Internet Protocol, or IP, addresses. Every computer, or host, on the Internet has an IP address assigned to it; that is, every host name refers to an IP address. A “domain name” is a logical name or host name assigned to an IP address and used as another type of addressing construct for identifying Internet nodes. Unlike IP addresses, domain names, such as BillSmith@aol.com and www.ultimateelectronics.com, are designed to easily be remembered and used by people. By way of illustration, IP addresses are generally machine readable numeric sequences that are 32 bits in length. A domain name service resolves domain names to IP addresses and vice versa.
The domain name service uses a client/server mechanism, with domain name resolvers as the clients and domain name servers as the servers, and is implemented as a distributed database, existing in a domain name space, whereby each domain generally keeps records only of its next-level subdomains. The domain space is organized hierarchically, with the root domain at the top and the rest of the structure branching from the root domain. All domain name resolvers have a pointer to the root domain (served by multiple servers), which in turn have pointers to all the top-level domains (those one level below the root domain), which in turn have pointers to their subdomains, so that any name within the name space can be queried and resolved efficiently.
In partitioned, packet-switched, distributed processing networks using DNS technology, traffic shaping or load balancing has continued to present challenges to network designers. For example, IP telephony traffic is directed by domain name servers to proxies that further direct the traffic to authoritative domains for the call request. Domain name servers, however, do not shape the call based on traffic. Core proxies that distribute calls to authoritative proxies do not shape traffic either. The current use of IP telephony is predominantly to make calls to individuals (e.g., sip:davidchavez@sip.avaya.com). As IP telephony becomes increasingly popular, users will use IP telephony to place calls to general business or enterprise addresses associated with contact centers (e.g., customer_service@sip.avaya.com) having multiple call servicing agents. For efficient service goals and objectives to be realized, IP telephony calls to contact centers will need to be distributed to agents and proxies to reflect current or anticipated traffic or loads. In other examples, similar problems exist when specific web addresses are too popular at certain intervals. In particular, server farms, for optimal operation, require some type of load balancing to substantially minimize the time required to respond to content requests.
Compared to packet-switched networks, a number of effective load balancing algorithms have been developed for circuit-switched networks. In circuit-switched telephony, incoming trunks are generally spread through the enterprise network of Private Branch Exchanges or PBXs. Within the enterprise, traffic can be shaped through PBX hierarchy or network services for call redirection/deflection. For example in Best Services Routing™ of Avaya, Inc., PBXs communicate with one another regarding their current estimated wait times for call servicing. When a call arrives, the estimated wait times are used to redirect the incoming call to an appropriate PBX. In Network Route™ of Avaya, Inc., an adjunct processor is used to acquire estimated wait times for a plurality of PBXs. Rather than have a call come into a first PBX and then have to redirect the call to a second PBX the adjunct processor uses SS7 technology to shape the Public Switched Telephone Network or PSTN routing so that the call is optimally directed at the outset to the PBX that is best able to handle it.
The load balancing/traffic shaping algorithms used for circuit-switched applications, however, are generally unsuitable for packet-switched applications due to the differing mechanisms used to direct or route incoming contacts. In circuit-switched applications, an OSI Layer 4 network is available to permit redirection of contacts optimally. In packet-switched applications, once a destination IP address is selected there are substantial costs involved with redirect the contact to a different IP address.